The invention relates to a water-soluble package and to its preparation. In particular the invention relates to liquid detergent enclosed within a water-soluble film.
Water-soluble packages are known and are disclosed, for example in GB-A-2305931 and W089/04282. In the agrochemical industry known water-soluble packages generally comprise either vertical form-fill-seal (VFFS) envelopes or thermoformed envelopes. In one of the VFFS processes, a roll of water-soluble film is sealed along its edges to form a tube, which tube is the heat sealed intermittently along its length to form individual envelopes which are filled with product and heat sealed. The thermoforming process generally involves moulding a first sheet of water-soluble film to form one or more recesses adapted to retain a composition, such as for example a solid agrochemical composition, placing the composition in the at least one recess, placing a second sheet of water-soluble material over the first so as to cover the or each recess, and heat sealing the first and second sheets together at least around the recesses so as to form one or more water-soluble packages.
JP-1029438 discloses a polyvinyl alcohol type film useful as a packaging material which has a coating of fine powder obtained by spraying an aqueous dispersion containing the powder on the surface of the PVA film. Suitable powders includes calcium carbonate, magnesium carbonate, clay, talc, silicic acid and kaolin. The coating is said to provide excellent slip and anti-blocking properties while retaining heat sealability and the film does not release the fine powder.
Generally, water-soluble packages suffer a number of disadvantages. First, as the packages are susceptible to moisture, the composition, which can be contained within the package, is limited. Secondly, the storage and transport of such packages must be carefully controlled as humidity in the atmosphere can weaken the structural integrity of the formed packages.
It is an object of the present invention to overcome at least some of the above disadvantages.
It has been surprisingly discovered that water-soluble packages have a tendency to stick together when a number of them are stored in close proximity over a period of time. A further discovery of the applicants is that when a secondary package containing a plurality of such stuck-together packages is subjected to external impact, then the likelihood of the packages maintaining their integrity, ie not rupturing or breaking, is greater then when compared with the situation where the packages have not stick together.
Accordingly, the invention provides a water-soluble package comprising a composition, such as for example a liquid detergent composition, enclosed within a water-soluble film, wherein at least a potion of a surface of the package includes a dusting of powder. Thus, when a plurality of such water-soluble packages are stored or transported in close proximity they will be less prone to stick together. Further, the invention provides a plurality of the water-soluble packages according to the invention packaged within a secondary pack.
In one embodiment of the invention, the powder has an average particle size of between 0.1 and 20 microns, suitably between 5 and 15 microns. Typically, a powder such as talc could be used, such a powder being well known. Other suitable materials include calcium stearate and zinc stearate. Alternatively a suitable fine grade of starch may be used. Generally the powder will be inert, and ideally easily dispersible in water.
The powder is generally applied at a rate of from 0.5 to 10 mg/100 cm2, preferably not more than 5 mg/100 cm2, more preferably in the range 1.25 to 2.5 mg/100 cm2.
In a preferred embodiment of the invention the film is a polyvinyl alcohol, or modified polyvinyl alcohol, film. Typically, the composition is a fluent composition such as for example a liquid, gel or paste. Preferably, each package will contain up to one liter of composition, ideally between 10 and 50 ml, most preferably between 15 and 30 ml. In an envisaged embodiment, the composition will include detergent suitable for use in the machine washing of laundry or dishes. The composition may include from 1 to 15%, generally up to 10% by weight water, ideally between 3 and 7% by weight water. Generally the packages of the invention will be resiliently deformable, and the powder will ideally coat or dust a substantial portion of the package surface.
Preferably the water-soluble package of the invention comprises a first sheet of water-soluble material moulded to form a body portion of the capsule, and a second sheet of water-soluble material superposed on the first sheet and sealed thereto by a closed seal along a continuous region of the superposed sheets, wherein at least a portion of the formed package includes an external coating or dusting of a powder. Typically, the fluent composition is a detergent liquid or gel suitable for use in the machine washing of fabrics or dishes.
The invention further relates to a process for producing a water-soluble package by thermoforming or vertical form fill seal (VFFS)techniques, the process being characterised in that the formed package is brought into contact with a powder such that that a dusting of fine powder is applied to at least a portion of a surface of the package. Typically, the powder is applied using a fluidised bed, by spraying or using a falling curtain.